This invention relates to mobile electric accessory apparatus for an automotive vehicle equipped with both a transceiver unit for wireless communication and another wireless receiver unit.
Recent advances in radio communications and semiconductor technology have been accompanied by an improvement in the performance of radio communications equipment. Progress has also been made in reducing the size and enhancing the capabilities of radio communications equipment. As a result, there has also been progress in the area of size reduction and capability enhancement of, e.g., television broadcast receivers in addition to AM/FM transceivers, and automobiles can now be equipped with both types of equipment. In order to assure that these apparatus will enjoy good reception at all times, a so-called "diversity system" is adopted in which each is provided with a plurality of antennas and the antenna giving the best reception is selected.
For example, Japanese Patent Application Laid-Open (KOKAI) No. 61-121601 discloses means for improving the reception of a mobile television unit, namely a television unit installed in an automobile. In view of the fact that locations at which an antenna can be installed in a vehicle are limited, this disclosure proposes adopting diversity reception by making joint use of an antenna for receiving FM broadcasts near the frequency bands of the broadcast waves, and an antenna for receiving low-frequency band television broadcasts.
However, this prior art disclosure does not take into account the antenna for a radiotelephone that can now be installed in an automobile thanks to recent advances in technology. A mobile telephone unit emits radio waves of considerable strength, and there are cases where the frequency of the radio waves transmitted and received by the mobile telephone are adjacent the television reception frequency (particularly in the vicinity of channel 62). Consequently, the radio waves emitted by the telephone apparatus can be received by the antenna for the television receiver. If the electric waves of the television broadcast are received in a weak condition, the radio waves from the telephone may interfere with television reception, thus resulting in a poor television picture.
Another problem that results from use of the mobile telephone is that a large amount of noise resembling a buzzing sound emanates from the television speaker at the same time, thus making it difficult to hear what is being said on the telephone.